Cystinosis, a genetic disease caused by dysfunction of cystine transport
across the lysosomal membrane

Cystinosis is a rare genetic disorder caused by mutations in the gene coding for cystinosin, a cystine transporter on the lysosomal membrane. Cystinosic patients show a massive lysosomal cystine accumulation that has adverse effects on their organs.

The treatment of those patients involves cysteamine, an aminothiol chemical that reacts with cystine in the lysosome and leads to the formation of cysteine and a mixed disulfide compound similar to lysine. This compound is exported out of the lysosome by PQLC2, a basic amino-acid transporter that was recently characterized in collaboration with Pr. B. Gasnier (Universités Descartes, Paris). This characterization was facilitated by the fact that the yeast possesses protein orthologues to cystinosin (Ers1) and PQLC2 (the Ypq1-3 transporters). The yeast is thus a very good model to study many aspects of cystinosis (Jézégou et al. 2012; Llinares et al. 2015).

Our current work aims to characterize the genes encoding additional proteins involved in elimination of lysosomal cystine.